1. Field of the Invention
The present invention generally relates to a magnetoresistance effect element, a substrate therefor, and a manufacturing method thereof, which element is used for a sensor capable of detecting a vector in a magnetic field such as in an electronic compass, a recording device, a signal processing device, and so on.
2. Description of the Related Art
As sensors, there are a magnetoresistance effect element (MR element) sensor, a magnetoimpedance element (MI element) sensor, a fluxgate sensor, and a semiconductor Hall effect sensor. For example, when an MI element is used for a sensor, the sensor can be made thin and miniaturized. In a case where an MR element is used for a sensor, the sensor can detect magnetic field intensity by a high frequency impedance change caused by a magnetic field when a high frequency current flows.
As the magnetic sensors, a giant magnetoresistance effect element (GMR element) and a tunneling magnetoresistance effect element (TMR element) have been utilized. In the GMR element, ferromagnetic layers and non-ferromagnetic layers are alternately stacked plural times, and magnetism is detected by utilizing a resistance change between the magnetization directions of adjacent two magnetic layers that are parallel and non-parallel caused by intensity of an external magnetic field. In the TMR element, plural magnetic thin film layers are formed by sandwiching an insulation layer therebetween, and electrons are transmitted through the insulation layer by tunneling while maintaining a spin. Then a magnetic field is detected by utilizing the fact that tunnel transmission coefficients are different between magnetized conditions.
Since the ferromagnetic tunnel effect has very high magnetic sensitivity, the effect can be used for a magnetic reproducing head of an HDD in ultrahigh-density magnetic recording. In addition, the ferromagnetic tunnel effect may be used for a magnetic sensor for a magnetic field measuring instrument of motors, for a car navigation system, and a magnetic solid memory device such as an MRAM (magnetic random access memory).
In Patent Documents 1 through 6, the technology of magnetic sensors is disclosed. In Patent Document 1, a thin film magnetic sensor is disclosed. In the sensor, in order to improve low magnetic field sensitivity of a granule film, the granule film is disposed on a slant surface of a supporting soft film. With this, the thin film magnetic sensor can detect plural magnetic fields. In Patent Document 2, a spin-valve magnetic head is disclosed. In the head, magnetic intensity between PIN layers is different due to a magnetizing method in a spin-valve structure. In order to solve the above problem, a proper thickness of a ferromagnetic film is used and heat treatment is applied to the film.
In Patent Document 3, a manufacturing method of a two-axial magnetic sensor is disclosed in which magnetic detecting directions are orthogonal. In the sensor, an array of permanent magnets is arranged in which the polarity of the permanent magnets is alternately disposed. In Patent Document 4, a magnetic sensor and a magnetic recording/reproducing apparatus using the sensor are disclosed. In the magnetic sensor, a spin-valve laminated film having high coupling and high thermal stability is provided. With this, a high-reliability sensor, a magnetic recording apparatus whose recording density is high, and a magnetoresistance effect recording head and a magnetoresistance effect reproducing head having high sensitivity and low noise are provided. In the sensor, Ir—Mn and Fe—Mn are used and a spin-valve structure is used.
Technologies in Patent Documents 5 and 6 are disclosed by the applicant of the present invention.
In Patent Document 5, a magnetic sensor and an azimuth detecting system using the sensor are disclosed. In this, the magnetic sensor is small-sized and light-weighted with high sensitivity. In the sensor, plural thin film magnetoresistance effect elements are arrayed in parallel which elements can obtain binary magnetization conditions. With this, the sensor can detect magnetism. The azimuth detecting system includes the magnetic sensors disposed on three axes, a vector detecting unit for detecting vectors of the three axes or more, a comparing unit for comparing an absolute value of the detected result with a predetermined threshold, and an informing unit for informing others of the compared result.
In Patent Document 6, a tunneling magnetoresistance effect element (TMR element) and an azimuth detecting system using the elements is disclosed. In this, the TMR element is small-sized and light-weight with high sensitivity. In the TMR element, a structure is disclosed which structure is needed to detect terrestrial magnetism with high sensitivity. In addition, similar to Patent Document 5, the azimuth detecting system includes the TMR elements disposed on three axes, a vector detecting unit for detecting vectors of the three axes or more, a comparing unit for comparing an absolute value of the detected result with a predetermined threshold, and an informing unit for informing others of the compared result. Further, the azimuth detecting system resets the TMR elements depending on the detected result of the detecting unit.
[Patent Document 1] Japanese Laid-Open Patent Application No. 2004-354182
[Patent Document 2] Japanese Laid-Open Patent Application No. 2002-117508
[Patent Document 3] Japanese Laid-Open Patent Application No. 2005-260064
[Patent Document 4] Japanese Laid-Open Patent Application No. 10-198922
[Patent Document 5] Japanese Laid-Open Patent Application No. 2003-167039
[Patent Document 6] Japanese Laid-Open Patent Application No. 2003-008101
As described above, the tunneling magnetic sensor using TMR elements has high sensitivity. In many cases, the tunneling magnetic sensor has a layer structure formed of a magnetic metal layer (soft layer), an insulation layer, and a magnetic metal layer (magnetization fixing layer), and the insulation layer is formed of an inorganic thin film of approximately 1 nm thickness. In addition, in the spin-valve structure, a magnetization state is fixed by an exchange interaction at a boundary surface between an anti-ferromagnetic layer and a magnetic layer. That is, tunneling probability is changed by a relative angle between the magnetization fixing layer and the soft layer. By the above change, a resistance value is changed, and a magnetic change of the soft layer is detected. The characteristics of the PIN layer are important along with the characteristics of the soft layer, and the characteristics of a magnetic sensor, a magnetic head, and an MRAM have been extremely increased by improvement of the above characteristics.
However, in the magnetic sensor, a monolithic layer structure and multi axes are required. That is, PIN layers each having a different magnetization direction must be adjacently disposed.